As those skilled in the art are aware, it is frequently necessary in the construction industry to precut wooden members at various angles and with a necessary high degree of precision. As an example, in precutting rafters for buildings, it is necessary to prepare such structural members with precise angles depending upon such factors as roof pitch and the type of roof being constructed. Other factors include design variables such as span and whether the roof is of exposed beam design. Skilled tradesmen can operate operate a hand saw so that straight true cuts are made across the width and through the thickness of a piece of material. However, even skilled artisans occasionally make errors in their cuts, particularly if a compound angle cut is required. Also, and even for skilled carpenters, making multiple cuts free hand or with only lines to follow would be difficult to do with accuracy. Thus, timbers or boards are sometimes wasted. Hence, it is desirable to cut in multiples on confirmation of the angle cut. Whether the board or beam is already in place or whether it is to be precut, the cutting line may be particularly hard to follow accurately if the rafter is large such as for example a 10.times.10 or 8.times.10 beam or if the rafter is already in place and must be cut from below. It can be extremely awkward for a carpenter working from below to make an accurate cut along the prescribed cutting line.
Numerous guide or miter box devices have been designed to facilitate the angular cutting of wooden members such as rafters and larger wooden structural members. The prior art devices typically include saw guide devices some of which include clamping means for holding the work piece. However, most miter devices are for finish work type angular cuts such as for molding and the like. In the field, a larger wooden structural member may have to be taken to a specially equipped lumber yard in order to have special angles cut on it. No prior art devices are known which are portable and which can accurately guide a hand saw or a chain saw through a stack of rafter members or along a compound angular cut in a timber or beam.
While prior art cevices are generally acceptable in terms of accuracy, they are typically relatively large and expensive and therefore not practical or satisfactory. In cutting rafters, for example, it is desirable to cut each end of the board before removing it from its work supporting surface by utilizing a portable saw guide which can be quickly and accurately attached at each end of the work piece.
Among the prior art patents are U.S. Pat. No. 4,031,794 which is a portable guide but the structure of which is not pertinent to the details of the instant invention. Other devices are shown in U.S. Pat. Nos. 4,325,278; 3,757,628; 2,773,523; 1,541,134; 1,280,203; and 2,705,029. Of the above listed patents, which are the only prior art of which applicant is aware, none are considered to be pertinent to the instant invention as described and claimed.